Investigation of the repeatability of tear osmolarity using an I-PEN osmolarity device

Abstract

PURPOSE: To investigate the repeatability of tear osmolarity in healthy Saudi subjects using an I-PEN osmolarity device. MATERIALS AND METHODS: Thirty typical male subjects with healthy eyes (27.4 ± 4.9 years) participated in the study. Eye abnormalities were tested with a slit lamp, and eye comfort was determined with the surface disease index. Measurements of the tear break-up time and phenol red thread tests were used for as exclusion criteria. The tear osmolarity test, using an I-PEN osmolarity system, was performed three times in the right eye of each subject with a 5 min' gap between tests. RESULTS: The average osmolarity test score was 303.8 ± 4.8 mOsm/L. Tear osmolarity measurements showed tear osmolarity of 280–299 mOsm/L, 300–309 mOsm/L, and 310–329 mOsm/L in 14 (46.7%), three (10%), and 13 (43.3%) subjects, respectively. Correlations among the three I-PEN measurements were significant (Spearman's correlation coefficient; r = 0.036, 0.501, and 0.603; P = 0.050, 0.006, and 0.001, respectively). The mean coefficient of variance among the three measurements was 4.4%. CONCLUSION: The mean measurement of an I-PEN tear osmolarity was 303.8 ± 4.8 mOsm/L which is in agreement with the range of those reported for healthy subjects. The I-PEN is reliable and has the advantage of portability (hand-held) compared to the other osmolarity systems.

Advances in Dry Eye Disease Examination Techniques

“…Shimazaki et al ( 78 ) studied the efficacy and safety of the handheld I-PEN in Japanese patients with dry eye disease and those without dry eye disease and found no correlations between the tear film osmolarity values obtained with the I-PEN system and any subjective or objective parameters of dry eye. Meanwhile, in the study of Fagehi et al ( 79 ), the mean measurement of I-PEN tear osmolarity was 303.8 ± 4.8 mOsm/L, which is in agreement with the range reported for healthy subjects. The I-PEN is reliable and has the advantage of portability compared to other osmolarity systems ( 79 ).…”

“…Meanwhile, in the study of Fagehi et al ( 79 ), the mean measurement of I-PEN tear osmolarity was 303.8 ± 4.8 mOsm/L, which is in agreement with the range reported for healthy subjects. The I-PEN is reliable and has the advantage of portability compared to other osmolarity systems ( 79 ). Park et al ( 80 ) obtained similar results, indicating that the I-PEN osmometer can be considered suitable for the use in clinical settings, with good performance in the diagnosis of dry eye.…”

“…Tavakoli et al found that, in vivo, both instruments displayed poor repeatability (83). Some studies have found that after treatment, the osmotic pressure of tears in patients with dry eye is significantly reduced (74)(75)(76)(77)(78)(79)(80)(81)(82)(83)(84)(85)(86). However, other studies have found that the osmotic pressure of tears does not change significantly after treatment (84)(85)(86)(87)(88).…”

“…Each subject is asked to close their eyelids gently for 30 s, and the disposable single-use sensor then softly makes contact with the palpebral conjunctiva from the lower eyelid at a 30° angle. By design, the I-PEN beeps after a few seconds and displays an osmolarity reading on the screen ( 78 , 79 ). Tear osmolarity is measured three times in the right eye of each subject with 5-min intervals between measurements.…”

Dry eye disease and tear film assessment through a novel non-invasive ocular surface analyzer: The OSA protocol

“…The NIBUT is taken as the time elapsed until the blur of the lines can be observed. Polaris ( 54 ), EasyTear Viewplus ( 55 ), TS ( 56 – 58 ) and Keratograph 5M produced similar average results relating to NIBUT in the study carried out by Bandlitz et al ( 11 ). Because Keratograph 5M is the only device that performs the NIBUT measurement fully automatically, it is the recommended instrument for the measurement of this parameter.…”